1. Field of the Invention
The presently disclosed subject matter relates to an apparatus, method, program and storage medium for image processing, and an image pickup apparatus, particularly to a technique for correcting a defective pixel among the pixels of an image pickup element.
2. Description of the Related Art
It has been a known fact that, when a pixel in an image pickup element is faulty, a defect corresponding to the fault occurs in an image. As a technique to solve this, there is known a defect correction process (the so-called address-registration-type defect correction process) in which the position of the pixel fault in the image pickup element is previously recorded in an image pickup apparatus (a camera) as the coordinates of the defect, and an image processing unit in the image pickup apparatus replaces the pixel at the recorded coordinates with the values or average value of the peripheral pixels.
Japanese Patent Application Laid-Open No. 2005-311732 discloses an image correction method in which correction patterns indicating the presence or absence of a defect in the peripheral pixels of a defective pixel to be corrected (sixteen kinds of correction patterns indicating the arrangement of pixels useable for interpolation) are previously determined, and four-bit information (correction pattern numbers) for selecting a correction pattern is stored along with the address of the defective pixel. Thereby, it is possible to calculate the pixel value of the defective pixel using non-defective peripheral pixels, which are specified by the correction pattern corresponding to the correction pattern number that is stored along with the address of the defective pixel.
Japanese Patent Application Laid-Open No. 2000-308080 discloses a color image pickup element whose color filter array is an array other than the Bayer array, in particular, a random array.
The color filter array of this color image pickup element is a three-color random array of red (R), green (G) and blue (B) that meets a restrictive condition that any one of the four sides of a pixel of interest adjoins a pixel having the same color as the pixel of interest. Thereby, it is possible to prevent an occurrence of a color moire, even if an object whose luminance varies periodically. Furthermore, it is possible to substantially block a resolution deterioration caused by the presence of an isolative pixel fault.